I'm just toying with the idea of going from a Case rotor to a Cat. I'd be looking at a used one. I'd like a source for some basic specs on the different model numbers. I assume the ones with an R are the ones with rotary seperators. Basically I'd like to know HP, cyl. size, and rotor size on the different models. Anything to stay away from in the 4 to 5 yr old models? Thanks a lot.